Stacked coplanar antenna array



Aug. 12, 1958 J. v. FISHER 2,347,569

STACKED COPLANAR ANTENNA ARRAY Filed May 28, 1954 2 Sheets-Sheet 1 INVENTOR. JOJ'EPH 14 /s/ree,

Unite This invention relates to antennas, and more particularly to awide band antenna suitable for reception of all television channels andalso suitable for FM reception.

A main object of the invention is to provide a novel and improved wideband antenna for television and FM, said antenna being simple inconstruction, involving a minimum of electrical and mechanical parts,and providing high gain over the entire spectrum employed for televisionand FM transmission.

A further object of the invention is to provide an improved high gain,wide band antenna which is inexpensive t fabricate, which is rugged inconstruction, which involves substantially no corrosive joints and whichis easily adjustable, particularly with respect to ultra high frequencychannels so that a desired sharpness of the ultra high frequency fieldpattern may be obtained by adjusting the antenna.

A still further object of the invention is to provide an improved highgain, wide band antenna array of the multiple bay type wherein thenumber of stacking harnesses is minimized.

A still further object of the invention is to provide an improved wideband, high gain antenna, suitable for reception of all televisionchannels and for FM channels, said anntena being neat in appearance,being relatively light in weight, and being arranged so that only onetransmission line is required over the entire spectrum received by theantenna.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

Figure l is a perspective view of an improved wide band antennaconstructed in accordance with the present invention.

Figure 2 is a top plan view of one of the bays of the antenna array ofFigure 1.

Figure 3 is a schematic diagram showing the equivalent electricalcircuit of the antenna array of Figure 1 and indicating the direction offlow of current in the antenna elements.

Figure 4 is a schematic diagram of the antenna array of Figure 1illustrating the dimensional relationships of the various elements ofthe antenna array, particularly with respect to the lower frequencyportion of the television channel spectrum.

Figure 5 is a schematic diagram similar to Figure 1,

and illustrating the dimensional relationships of the rates Patent 0 inconstruction, and are separated by substantially equal verticalspacings.

Referring to Figure 2, the construction of the top bay 13 isillustrated, said top bay comprising a straight reflector bar 17 ofconductive material, for example, of aluminum tubing, and a pair ofdipole elements, designated at 18, 18, each dipole element comprising aconductive rod of aluminum or similar material, formed at anintermediate portion thereof with a Ushaped, relatively narrow loop ofsubstantial length, shown at 19. Respective insulators 20, 20 rigidlyconnect the bight portions of the loops 19, 19 to the reflector bar 17,the loops 19 being symmetrically located on opposite sides of the midpoint of the reflector bar 17. The mid point of the reflector bar 17 isconnected by a rigid bracket rod 21 to an insulator 22, the inner endsof the respective dipole elements 18, 18 being secured to the oppositeends of the insulator 22, as shown in Figure 2.

The outer portions of the respective dipole elements 18, 18 aresubstantially \I-shaped, as shown at 23, 23, facing away from thereflector bar 17. Respective rigid connecting rods 24, 24 connect thereflector bar 17 to insulators 25- secured to the bends of the \I-shapedportions 23 of the dipoles.

As is clearly shown in Figure 2, the inner portions 26 of the respectivedipoles are inclined inwardly toward the reflector bars 17 and togetherdefine a V-shaped configuration similar to the configurations of therespective outer, V-shaped dipole portions 23, 23.

All the elements thus far described, comprising the reflector bar 17,the dipoles 18, 18, the respective loops 19, 19, and the bracketelements 24, 24 and 21 are in the same horizontal plane.

As shown in Figure 2, the reflector bar 17 is of a length substantiallyequal to one-half the wave length of the mid channel of the lowerportion of the television spectrum, namely, the spectrum includingchannels 2 to 6. The distance between the outer ends of the dipoles 18,18 is substantially equal to the length of the reflector bar, namely, toone-half of the wave length of the mid channel of the lower portion ofthe television spectrum.

As is further shown in Figure 2, the lengths of the V- shaped portions23, 23 and the V element defined by the inner ends 26, 26 of the dipolesare substantially equal and correspond to one-half the wave length of afrequency substantially in the middle of the upper V. H. F. televisionband, namely, the portion of the television spectrum including channels7 to 13. Obviously, since the length of the V-shaped portions 23, 23 andthe V-shaped portion defined by the inner portions 26, 26 of the dipolesare equal, each of the V-shaped elements thus defined has a lengthsubstantially one-third that of the reflector bar 17.

The spacing of the main portions of the dipole elements 18, 18 from thereflector bar 17 is, of course, determined by the lengths of the bracketbars 24, 2 -1, 21 and the loops 19, 19. In a typical embodiment of theinvention, this length was approximately equal to a quarter wave lengthof a middle channel in the upper portion of the V. H. F. televisionspectrum, namely, that portion of the television spectrum including thechannels 7 to 13.

Obviously, a considerable range of dimensions may be employed inchoosing the proper lengths of the reflector bar 17 and the dipoleelements 13, 18. For example, the reflector bar 17 may be of a lengthequal to the length of one'half of the wave length for the lowesttelevision channel of the spectrum to be covered and the lengths of theV-shaped portions 23, 23, as well as the intermediate V-shaped portiondefined by the inner end elements 26, 26 of the dipoles may be inaccordance with the wave length of a particular channel in the upperportion of the V. H. F. television band, namely, in the bandincludingchannels 7 to 13, the spacing of the dipole elements from the reflectorbar being similarly governed by the selected upper V. H. F. channelfrequency and the spacing being one-quarter of the wave length of saidselected frequency.

The inner ends of the dipoles of the bays 13 and 14 are connected by apair of vertical harness conductors 27 and 28, and similarly, the innerends of the dipoles of the bays 15 and 16 are connected by a pair ofvertical harness conductors 29 and 3% Suitable insulators 31 and 32connect the intermediate portions of harness conductors 27, 28 and 29,3d. The intermediate portions of the harness conductors Z7 and 29 areinterconnected by a vertically extending additional rigid harnessconductor rod member 33, and similarly, the intermediate portions of theharness conductors 23 and 30 are intenconnected by a verticallyextending, rigid harness conductor rod member 34 extending parallel tothe harness conductor rod member 33. The intermediate portions of theharness conductor rods 33 and 34 are secured together by a terminalinsulator 35 provided with respective terminals connected to therespective harness conductor rods 33 and 34, to which the transmissionline wires are connec ted, whereby the antenna array may be suitablyconnected to the terminals of a television receiver. The terminalinsulator 35 is rigidly braced to the mast 12; by a horizontallyextending bracket rod 36 connecting the intermediate portion of theinsulator 35 to a suitable clamp bracket 37 secured on the mast 12.

Adjustably mounted on the respective vertically extending harnessconductor rods 33 and 34 are the respective pairs of ultra-highfrequency tuning loops 38, 39 and 4t), 4-1, said tuning loops beingvertically movable and being provided with suitable means for securingthe loops in adjusted positions on the harness conductors 33 and 34. Asshown in Figure 1, the tuning loops 38, 39, tll and 41 extend inhorizontal planes and are relatively small in diameter.

However, the U. H. F. bow loop elements 38, 39, 4t) and 41 are angularlyadjustable so that they can be set at any desired angle so as to adjustthe sharpness of the U. H. F. field pattern of reception.

The bracket rods 21, extending perpendicularly from the mid point of therespective reflector rods 17 are electrically connected to saidreflector rods, forming a part thereof, and serve to keep out sidesignals, making the antenna array sharply directional. Similarly, therod elements 24, 24 are electrically connected to the reflector bars 17,for the same purpose.

Referring now to Figure 3, it will be seen that the transmission lineconductors, shown at 4-2 and 43 are connected to the intermediateportions of the respective harness conductor rod elements 33 and 34whereby respective circuits are completed between the televisionreceiver input circuit and the ether. From this schematic diagram, thecurrent can be considered as entering the antenna array at the rightends of the dipoles 13, 14, 15 and 16, and circulating through therespective dipole elements in the directions indicated by the arrows.Thus, the currents in the right end portions of the upper dipoleelements 13 and 14 enter the top end of the harness condoctor 34- =andpass to the television receiver input circuit through the transmissionline conductor 43, the current leaving the input circuit of the receiverthrough the transmission line conductor 42 and entering the harncssconductor 33. The currents leave the ends of the harness conductor 33and pass through the left end portions of the dipole elements of thebays l3, l4, l and 16 and. discharge into the ether.

it will be noted that each structural element of the array has anelectrical function, and that a minimum amount of mechanical parts arethus required in order to complete the antenna assembly. This not onlyreduces the cost of the assembly but also considerably lightens itsweight, making it easier to erect the antenna and rotate theasame toobtain. the desired orientation The lightness.

of the antenna also makes it suitable for use with antenna rotatingmechanisms of conventional type.

As shown in Figure 4, the vertical spacing between the bays 13, 14, 15and 16 is preferably such that with respect to the lower portion of theV. -H. F. television spectrum, the vertical spacing between the bays isequal to one-fifth of a wave length, for example, the mid wave length inthis portion of the band, or, alternatively, onefifth of the lowest wavelength in the band. Figure 5 illustrates the wave length distributionwhich may be employed in a typical antenna array according to thepresent invention, with reference to the television channels in theupper portion of the spectrum, namely, channels 7 to 83.

An important feature of the present invention is that the U-shapedelements 1) act not only as matching stubs but also take the place ofthe supporting rods and phasing harnesses employed in previously knownantenna arrays.

While a specific embodiment of an improved broad band antenna has beendisclosed in the foregoing description, it will be understood thatvarious modifications within the spirit of the invention may occur tothose skilled in the art. Therefore, it is intended that no limitationsbe placed on the invention except as defined by the scope of theappended claims.

What is claimed is:

' 1. In a broad band antenna of the character described, a straightreflector bar, a pair of dipole elements, each dipole element comprisinga conductor rod formed at an intermediate portion thereof with aU-shaped, relatively narrow loop of a length equal to one quarter of awave length of an upper V. H. F. television frequency and having itsbight portion located closely adjacent to said reflector bar, andrespective insulators rigidly and supportingly connecting the bightportions of said loops to the reflector bar with the dipole elements andreflector bar disposed in the same horizontal plane and with the dipoleelements spaced symmetrically relative to the mid point of saidreflector bar, the arm portion of each dipole element located outwardlyof its loop being substantially V-shaped and facing away from thereflector bar, said V-shaped outer arm portions being in the commonhorizontal plane of the loops and reflector bar.

2. In a broad band antenna of the character described, a straightreflector bar, a pair of dipole elements, each dipole element comprisinga conductor rod formed at an intermediate portion thereof with aU-shaped, relatively narrow loop of a length equal to one quarter of awave length of an upper V. H. F. television frequency and having itsbight portion located closely adjacent to said reflector bar, andrespective insulators rigidly and supportingly connecting the bightportions of said loops to.

the reflector bar with the dipole elements and reflector bar disposed inthe same horizontal plane and with the dipole elements spacedsymmetrically relative to the mid point of said reflector bar, the armportion of each dipole element located outwardly of its loop beingsubstantially V-shaped and facing away from the reflector bar, saidV-shaped outer arm portions being in the common horizontal plane of theloops and reflector bar, the arm portion of each dipole element locatedinwardly of its loop being inclined inwardly toward the reflector barand being in said common horizontal plane.

3. In a broad band antenna of the character described, a straightreflector bar, a pair of dipole elements, each dipole element comprisinga conductor rod formed at an reflector bar, the arm portion of eachdipole element located outwardly of its loop being substantiallyV-shaped and facing away from the reflector bar, said V-shaped outer armportions being in the common horizontal plane of the loops and reflectorbar, respective insulators connected to the bends of said V-shapedportions, the arm portion of each dipole element located inwardly of itsloop being inclined inwardly toward the reflector bar and being in saidcommon horizontal plane, an insulator rigidly connecting the ends ofsaid last-named arm portions, and respective conductive support elementsrigidly and supportingly connecting said last-named insulator and theinsulators at the bends of the V-shaped outer arm portions of the dipoleelements to the reflector bar and being electrically connected to saidreflector bar.

4. In a broad band antenna of the character described, a verticalsupport, a pair of antenna bays stacked one above the other and securedto said support, each antenna bay comprising a straight reflector bar, apair of dipole elements, each dipole element comprising a conductor rodformed at an intermediate portion thereof with a U- shaped, relativelynarrow loop of a length equal to one quarter of a wave length of anupper V. H. F. television frequency and having its bight portion locatedclosely adjacent to said reflector bar, respective insulators rigidlyand supportingly connecting the bight portions of said loops to thereflector bar with the dipole elements and reflector bar disposed in thesame horizontal plane and with the dipole elements spaced symmetricallyrelative to the mid point of said reflector bar, the arm portion of eachdipole element located outwardly of its loop being substantiallyV-shaped and facing away from the reflector bar, said V-shaped outer armportions being in the common horizontal plane of the loops and thereflector bar, the arm portion of each dipole element located inwardlyof its loop being inclined inwardly toward the reflector bar and beingin said common horizontal plane, an insulator rigidly connecting theends of said last-named arm portions, and respective conductive supportelements rigidly and supportingly connecting said last-named insulatorand the bends of the V-shaped outer arm portions of the dipole elementsto the reflector bar and being electrically connected thereto, andrespective vertically extending harness conductors interconnecting theinner ends of the dipole elements.

5. In a broad band antenna of the character described, a verticalsupport, a pair of antenna bays stacked one above the other and securedto said support, each antenna bay comprising a straight reflector bar, apair of dipole elements, each dipole element comprising a conductor rodformed at an intermediate portion thereof with a U-shaped, relativelynarrow loop of a length equal to one quarter of a wave length of anupper V. H. F. television frequency and having its bight portion locatedclosely adjacent to said reflector bar, respective insulators rigidlyand supportingly connecting the bight portions of said loops to thereflector bar with the dipole elements and reflector bar disposed in thesame horizontal plane and with the dipole elements spaced symmetricallyrelative to the mid point of said reflector bar, the arm portion of eachdipole element located outwardly of its loop being substantiallyV-shaped and facing away from the reflector bar, said V-shaped outer armportions being in the common horizontal plane of the loops and reflectorbar, the arm portion of each dipole element located inwardly of its loopbeing inclined inwardly toward the reflector bar and being in saidcommon horizontal plane, an insulator rigidly connecting the ends ofsaid last-named arm portions, and respective conductive support elementsrigidly and supportingly connectting said last-named insulators and thebends of the U-shaped outer arm portions of the dipole elements to thereflector bar and being electrically connected thereto, respectivevertically extending harness conductors interconnecting the inner endsof the dipole elements, and relatively small, closed conductor loopelements adjustably mounted on the harness conductors.

6. In a broad band antenna of the character described, a verticalsupport, a plurality of antenna bays stacked one above the other andsecured to said support, each antenna bay comprising a straightreflector bar, a pair of dipole elements, each dipole element comprisinga conductor rod formed at an intermediate portion thereof with aU-shaped, relatively narrow loop of a length equal to one quarter of awave length of an upper V. H. F. television frequency and having itsbight portion located closely adajacent to said reflector bar,respective insulators rigidly and supportingly connectting the bightportions of said loops to the reflector bar with the dipole elements andreflector bar disposed in the samehorizontal plane and with the dipoleelements spaced symmetrically relative to the mid point of saidreflector bar, the arm portion of each dipole element located outwardlyof its loop being substantially V-shaped and facing away from thereflector bar, said V-shaped outer arm portion being in the commonhorizontal plane of the loops and reflector bar, the arm portion of eachdipole element. located inwardly of its loop being inclined inwardlytoward the reflector bar and being in said common horizontal plane, aninsulator rigidly connecting the ends of said last-named arm portions,and respective conductive support elements rigidly and supportinglyconnecting said last-named insulators and the bends of the V-shapedouter arm portions of the dipole elements to the reflector bar and beingelectrically connected thereto, respective, vertically extending harnessconductors interconnecting the inner ends of the dipole elements, saidantenna including four bays stacked one above each other, said harnessconductors including vertical conductors connecting the inner ends ofthe dipoles of the adjacent top and bottom pairs of bays, respectiveadditional vertically extending harness conductors connecting the midpoint of the first-mentioned vertical conductors, and relatively small,closed conductive loop elements 'adjustably mounted on said additionalvertically extending harness conductors.

References Cited in the file of this patent UNITED STATES PATENTS1,934,182 Franklin Nov. 7, 1933 2,586,276 Umstead Feb. 19, 19522,655,599 Finneburgh' Oct. 13, 1953 OTHER REFERENCES Radio Electronics,page 67, November 1951. Radio Electronics, page 155, January 1953.

